John Hattie’s influential 2008 book Visible Learning: A synthesis of over 800 Meta-Analyses Relating to Achievement is believed to be the world’s largest evidence-based study into the factors which improve student learning. Involving more than 80 million students from around the world and bringing together 50,000 smaller studies, the study found positive teacher-student interaction is the most important factor in effective teaching.

The most important issue is scalability. There is a rich source of educational research, there are so many excellent educators in our schools and universities, and there is so much we know about what this success looks like. The missing ingredient is how to scale this success.